Valorization of rambutan (Naphelium lappaceum L.) peel: an enzymatic approach toward a biopolymer absorbent foam

This study explored rambutan peel (RP) as a sustainable alternative food bioproduct to extract cellulose for application in packaging. The RP was pre-extracted with Soxhlet apparatus and the residual fiber was treated with synergetic enzyme (xylanase-laccase) to produce cellulose. The synergetic enzymatic treatment before sodium chlorite bleaching reduced chemical input by 28% with a high crystallinity index. The study showed RP contains a high amount of lignin (> 30%) followed by α-cellulose of 28.3 ± 0.6% and hemicellulose (>19%). The thermogravimetric analysis showed good thermal properties with the maximum mass loss of 54%-59% occurring between 332 °C to 338 °C. The Soxhlet-assisted enzyme bleached cellulose fibers were combined with gum tragacanth (in the ratio of 1:1) to prepare a foam as an absorbent for meat packaging. The pore distribution in the foam was visualized in 3D by synchrotron radiation X-ray tomography, and the crystallinity by Wide-angle X-ray scattering. The as-prepared foam exhibited weight loss, drip loss and swelling properties similar to that of commercial absorbent after 4 days of meat storage. The enzymatic biorefinery approach is promising for the valorization of rambutan peel and other lignocellulosic biomass. The cellulose demonstrates great potential for application in the food industry as an absorbent for meat packaging.